Rest Of Cards For Cells And Microscopy Flashcards
What is a cell
Things that make up all living organisms / most simple organism
What is the bacterial cell wall made out of
Peptidoglycan
What are plasmids
Rings of DNA floating in cytoplasm
3 differences between prokaryotic cells and eukaryotic cells
- Bacteria cells have peptidoglycan cell wall and animal cells don’t have a cell wall and plant cell has cellulose cell wall
- Eukaryotic cells have a true nucleus whereas bacterial cells have circular chromosomes and plasmids to carry DNA
- bacterial cells lack cell membrane bound organelles, which plant and animal cells have eg: mitochondria
Magnification triangle
I
A. M
If you continually increase the magnification of an image beyond a certain point, the detail does not increase but rather the detail is …. The ability of a microscope to let us see the …… is called the ……….
Lost
Detail
Resolution
How do electron microscopes work
Pass a beam of electrons through a specimen to investigate the detail of structures inside cells.
Why might electron microscopes be better then light microscopes
Electron microscopes have a much bigger resolution, therefore we can see in greater detail. This has increased our understanding of cell structures
Many cells need ……, ….., ……….. along with other substances to enter through the cell …….. to perform their …….. Cell metabolism also produces …………….. such as carbon dioxide and nitrogen which needs to leave the cell. The cell membrane also prevents the ………. Of other molecules. Therefore, we say that cell membrane is selectively permeable
Oxygen
Water
Mineral ions
Membrane
Function
Waste products
Movement
Many substances move in and out of cells by
Diffusion
What is diffusion
The random movement of a substance from a high concentration to a low concentration (moves down a concentration gradient)
What happens As concentration increases
Speed of diffusion increases. Because larger diffusion gradient
What happens as surface area increases
Speed of diffusion increases as more surface area available for particles to diffuse through.
What happens as temperature increases
The speed of diffusion increases. Because the particles have more kinetic energy which makes them move out and spread faster
What do multi-celled organisms need
A large enough surface area to volume ratio to exchange substances such as water, glucose and ions
Multi celled organisms have developed special ………………. In their body to exchange substances efficiently eg: gas exchange system (………, ………)
Exchange surfaces
Lungs
Trachea
What is an organ
À structure made up of several different types of tissue that carries a particular function
Organs ……. Together, forming organ systems to carry out a ………
Operate
Function
What is a stem cell
A cell that is undifferentiated which means it has the ability to specialise into many other types of cell and can continue dividing by cell division to produce more stem cells
Embryonic stem cells can be collected from
Embryos
In adult animals most stem cells have changed permanently into ………………… cells but some can be collected from bone marrow which can only differentiate into blood cells
Specialised
Where can stem cells be found in plant cells
In each if the apical growing points and meristems at the end of shoots and roots.
Stem cell benefits
Treating leukaemia- chemotherapy and radiotherapy destroy white blood cells in the patients body, stopping bone marrow producing new blood cells. A bone marrow transplant containing stem cells from a matching donor allows healthy blood cells to. Made in the patient
Risks of stem cells
Risk of infection from the environment and Donor as chemotherapy and radiotherapy leave patient with no immune system
Stem cells may divide in a uncontrolled manner leading to formation of tumours or development of unwanted cells
Transfer diseases or viruses from other animals
Some people have ethical issues with use of embryonic stem cell use
Advantages of embryonic stem cells
Easy to obtain
Plentiful
Differentiate into many types of cell
Negatives of embryonic stem cells
Ethical considerations
Eg: “playing God” (only god has the right to create life)
Killing human life of embryos
Human rights
Advantages of bone marrow stem cells
No ethical concern
Negatives of bone marrow stem cells
Can only differentiate into blood cells
Sources of stem cells
Embryos
Umbilical cord blood
Bone marrow
A difference between animal and plant stem cells
Plant cells can redifferentiate and animal cells cannot
A similarity between animal and plant stem cells
The ability to become specialised cells
What does resolution mean
Ability to see fine detail
